Plastic film has long been a popular material for packaging applications. Plastic bags, in particular, have found broad application. Moreover, they have remained an economical type of packaging, because of the relatively low cost of the basic plastic materials and the low cost of manufacturing the plastic bags therefrom, owing to the efficient application of mass production techniques. However, the use of plastic bags has been limited, to some extent, by the fact that the thin plastic films utilized for such bags lack sufficient rigidity to permit the bag to stand upright, in an opened position, when empty.
In certain applications, for example, supermarket shopping bags and bags utilized in fast food restaurants, it is essential that bags used for merchandise be capable of standing upright and be self-supporting while empty. Individuals selling merchandise can then concentrate on handling the merchandise with both hands, instead of having to fumble wth the bag in an effort to support it while trying to fill it. For this reason, supermarkets, for example, have either tended to continue utilizing more rigid paper bags, or they have adopted plastic bags, but utilize a special supporting stand for the bags while they are being filled.
In U.S. Pat. No. 3,437,258, there is disclosed a self-supporting liquid-filled bag. The bag includes front and rear walls which are folded to form a bottom gusset. The lateral edges of the front and rear walls are sealed together, and a diagonal weld is formed in the lower corner of each wall so as to seal the wall to the gusset along each weld. As the bag is filled with liquid, the diagonal welds at the corners of the gusset cause the bottom of the bag to spread outwardly, forming a stable base for the liquid-filled bag.
Although the bag construction of U.S. Pat. No. 3,437,258 permits a liquid-filled bag to stand upright, it does not provide a satisfactory construction for supporting an empty bag in an upright position while it is being filled with solid materials. Even if the bottom of the bag is spread open so as to form a stable base, the front and rear walls do not have adequate support, and a person filling such a bag with solid items must constantly keep opening it.
Broadly, it is an object of the present invention to overcome the disadvantages of prior art plastic bags of the type described. It is specifically contemplated that the present invention provide a free-standing bag which will remain open when empty, so that it may be filled with solid materials, without the need to support the bag in any way.
It is another object of the present invention to provide such a plastic bag which is convenient and reliable in use, yet inexpensive in construction.
In accordance with the present invention, a plastic bag is constructed from a front and rear wall which are folded upwardly at the bottom to form a gusset. The front and rear walls are sealed together along their entire lateral margins, except that the upper portion of each wall is provided with an unsealed flap or cuff portion. Diagonal welds are then formed in the lower corner of each wall, so as to seal the wall to the underlying gusset wall. To complete the bag, each cuff portion is folded donwardly over the corresponding wall. Conveniently, the cuff portions are provided with cutout openings. After the bag is filled, the cuff portions may then be unfolded and used as carrying handles, with the cut-out openings serving as hand holes.
It is a feature of the present invention that the downwardly folded cuff portions lend themselves to the front and rear walls, whereby when an empty bag is opened, it stands freely in an open, self-supporting position .